Evaluation of Comorbidities and Treatment Outcome in Various Subtypes of Lichen Planus: A Single-Center Retrospective...

Background: Lichen planus (LP) is a chronic inflammatory dermatosis with multiple clinical variants involving the skin, mucous membranes, nails, and hair follicles. Methods: We conducted a retrospective, descriptive study of patients diagnosed with LP at a tertiary referral center from January 2011 to December 2024. Inclusion required concordance between clinical presentation and histopathologic findings. Demographic characteristics, LP subtypes, anatomical involvement, comorbidities, therapeutic approaches, and treatment outcomes were extracted from electronic health records. In addition, an exploratory sensitivity analysis restricted to patients with a single LP subtype was performed to allow for independent subgroup comparisons, and a modified Charlson Comorbidity Index (CCI) based on available comorbidity domains was calculated. Pairwise multivariable logistic regression models adjusted for age, sex, and outcome-specific modified CCI were performed for selected comorbidities. Results: A total of 754 patients were included (mean age 53.1 years), with cutaneous LP (cLP), oral LP (oLP), genital LP (gLP), and lichen planopilaris (LPP) being the most frequent subtypes; a total of 620 had a single major LP subtype and were included in the mutually exclusive analysis. In these groups, modified CCI, age-adjusted modified CCI, and overall comorbidity count differed significantly across subtypes (Kruskal-Wallis p < 0.001). After adjustment in pairwise models, cLP-only showed higher odds of malignancy compared with oLP-only, gLP-only, and LPP-only and higher odds of diabetes mellitus compared with all other pure subtypes. Most other comorbidity comparisons were non-significant or imprecise because of low event numbers. Topical glucocorticoids were the most frequently used treatment, and treatment responses varied by subtype, being more effective in cLP and gLP compared to LPP. Topical calcineurin inhibitors demonstrated the highest response rates in gLP. Acitretin was most effective in cLP, whereas isotretinoin showed favorable responses in oLP. Conclusions: This large, histopathologically confirmed cohort highlights distinct differences in comorbidity patterns, anatomical involvement, and therapeutic response across LP subtypes. Treatment outcomes vary substantially by subtype, underscoring the need for individualized management strategies. Prospective studies are warranted to further elucidate subtype-specific disease associations and optimize treatment approaches.